TABLE 2.
Regression coefficients (95% CIs) for cognitive function by quartiles of iron intake among Chinese adults aged ≥55 y who participated in the China Health and Nutrition Survey1
| Iron intake quartiles | |||||
|---|---|---|---|---|---|
| 1 (low intake; median: 14.6 mg/d) | 2 (19.3 mg/d) | 3 (23.7 mg/d) | 4 (high intake; 31.7 mg/d) | P-trend | |
| Global cognitive function | |||||
| Model 1 | 0.00 | −0.26 (−0.61, 0.09) | −0.74 (−1.11, −0.37) | −1.49 (−1.89, −1.09) | <0.001 |
| Model 2 | 0.00 | −0.36 (−0.73, 0.01) | −0.59 (−0.98, −0.20) | −0.90 (−1.32, −0.47) | <0.001 |
| Model 3 | 0.00 | −0.36 (−0.74, 0.01) | −0.58 (−0.97, −0.19) | −0.89 (−1.32, −0.47) | <0.001 |
| Model 4 | 0.00 | −0.39 (−0.77, −0.01) | −0.55 (−0.95, −0.15) | −0.90 (−1.33, −0.47) | <0.001 |
| Sensitivity analysis | 0.00 | −0.39 (−0.75, −0.03) | −0.52 (−0.90, −0.14) | −0.85 (−0.13, −0.44) | <0.001 |
| Verbal memory score | |||||
| Model 1 | 0.00 | −0.31 (−0.55, −0.06) | −0.56 (−0.82, −0.30) | −0.98 (−1.26, −0.69) | <0.001 |
| Model 2 | 0.00 | −0.33 (−0.60, −0.06) | −0.44 (−0.72, −0.16) | −0.61 (−0.91, −0.30) | <0.001 |
| Model 3 | 0.00 | −0.32 (−0.59, −0.05) | −0.43 (−0.72, −0.15) | −0.60 (−0.90, −0.29) | <0.001 |
| Model 4 | 0.00 | −0.34 (−0.61, −0.06) | −0.40 (−0.69, −0.12) | −0.60 (−0.92, −0.29) | <0.001 |
| Sensitivity analysis | 0.00 | −0.32 (−0.58, −0.05) | −0.41 (−0.69, −0.13) | −0.59 (−0.89, −0.28) | <0.001 |
n = 4852. Regression coefficients (95% CIs) were estimated with mixed-effects regression models with different levels of adjustment. Model 1 adjusted for age, gender, and energy intake. Model 2 further adjusted for intake of fat, smoking, alcohol drinking, income, urbanicity, education, and physical activity. Model 3 further adjusted for intakes of fruit and vegetables. Model 4 further adjusted for BMI and hypertension. The sensitivity analysis model 4 further adjusted for diabetes and stroke after excluding those with a global cognitive function score ≤4. All the adjusted variables were treated as time-varying covariates.